popwindow 动画取消奔溃报错java.lang.NullPointerException ViewRootImpl.drawAccessibilityFocusedDrawable

现在APP中用到popwindow的地方很多，为了美化体验效果，很多动画的展示和取消都加上了动画效果；下面我就来说下我遇到的问题以及解决的方法；

cancelAnimation.addAnimation(new AlphaAnimation(1.0f, 0.0f));
cancelAnimation.addAnimation(new ScaleAnimation(1, 1, 1, -1));
cancelAnimation.setDuration(executeTime);
cancelAnimation.setAnimationListener(new Animation.AnimationListener() {
    @Override
    public void onAnimationStart(Animation animation) {
        mScrollView.setVisibility(View.VISIBLE);
    }

    @Override
    public void onAnimationEnd(Animation animation) {
        mScrollView.setVisibility(View.GONE);
       
dismiss();      
        
 } @Override public void onAnimationRepeat(Animation animation) { }});      

上面我是实现了动画延伸和渐变来取消popwindow，在动画结束回调dismiss();

在Android 4.4以上是不会出现任何问题；但是在Android 4.1左右的版本就会在取消是奔溃：

java.lang.NullPointerException

#5367 09-20 03:38:07.999 17478 E CrashReport         at android.view.ViewRootImpl.drawAccessibilityFocusedDrawableIfNeeded(ViewRootImpl.java:2596)

#5368 09-20 03:38:07.999 17478 E CrashReport         at android.view.ViewRootImpl.onHardwarePostDraw(ViewRootImpl.java:2183)

#5369 09-20 03:38:07.999 17478 E CrashReport         at android.view.HardwareRenderer$GlRenderer.draw(HardwareRenderer.java:1233)

#5370 09-20 03:38:07.999 17478 E CrashReport         at android.view.ViewRootImpl.draw(ViewRootImpl.java:2420)

#5371 09-20 03:38:07.999 17478 E CrashReport         at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2274)

查看网上说的是popwindow调用dismiss()方法时报错；我理解为时在动画结束回调时Android4.1版本的是在子线程回调；

所以在调用dismiss();时我们加上handle试下让它在主线程执行；

cancelAnimation.addAnimation(new AlphaAnimation(1.0f, 0.0f));
cancelAnimation.addAnimation(new ScaleAnimation(1, 1, 1, -1));
cancelAnimation.setDuration(executeTime);
cancelAnimation.setAnimationListener(new Animation.AnimationListener() {
    @Override
    public void onAnimationStart(Animation animation) {
        mScrollView.setVisibility(View.VISIBLE);
    }

    @Override
    public void onAnimationEnd(Animation animation) {
        mScrollView.setVisibility(View.GONE);
        new Handler().post(new Runnable() {
            @Override
            public void run() {
                dismiss();
            }
        });
    }

    @Override
    public void onAnimationRepeat(Animation animation) {

    }
});      

果真加了之后再Android 4.1的手机上就不在出现奔溃了